Light-weight metal boat



Nov. 20, 1962 R. P. SWANSON 3,064,283

LIGHT-WEIGHT METAL BOAT Filed Sept. 27, 1960 IN V EN TOR.

26 5 ROGER P. SWANSON BY so @fW zw w ATTORN EYS Stat listens 3,654,233 LIGHT-WE GET METAL BGAT Roger P. Swanson, Lex ngton, Mass, assigner to Alumnkit C0,, ind, Salem, Mass, a corporation of Massaehusetts Filed Sept. 27, 1969, Ser. No. 58,76 3 11 Claims. (Ci. 96)

This invention is an improvement in boat construction, and more particularly in the construction of aluminum or similar light weight metal boats having a hull of onepiece construction.

The past fifteen years has seen a great increase in boa"- ing activities among the general population. As a result, for some years now there has been a substantial demand for a small, light-weight, sturdy craft which may be easily transported and which will require little attention and upkeep. Aluminum or similar light-weight metals have been tried, and with the development of special alloys, have been found to be generally suitable for the construction of such boats from the points of view of strength and weight. However, their high cost has prevented their more universal acceptance.

One of the reasons for the high cost is that, in order to achieve sufiicient strength in a one-piece hull of lightweight metal, it has hitherto been necessary to form the hull with compound curves. Such hulls, however, are very difiicult to make because the metal can accommodate only so much deformation, and they are expensive due to the extremely high cost of the dies necessary to form such hulls. Many attempts have been made to make such hulls without compound curves, but these have been essentially weak and unless loaded down with massive braces, etc., such hulls have not been sufhciently rigid to withstand the excessive vibrations and jarrings which an outboard motor, for instance, causes.

Accordingly one object of my invention is to provide a light-weight metal boat which is suited to properly withstand the vibration set up by an outboard motor attached to its transom.

Another object of my invention is to provide a lightweight metal boat which will have substantial buoyancy and which will not sink when swamped.

Still another object of my invention is to provide a light-weight metal boat which will be of rigid construction, yet will be formed without compound curves and without a great number of braces.

Yet another object of my invention is to provide a light-weight metal boat which will be rigid yet having a hull of one-piece construction.

In the accomplishment of these and other objects of my invention in a preferred embodiment thereof, I construct an aluminum boat of pointed bow design having a flat bottom and side walls bent together toward the bow in a simple curve. The walls are joined at the stern by a transom, also of fiat aluminum. 1 construct three seat members joining the side walls and add finishing decorative members. I employ three parallel keels running substantially the whole length of the fiat bottom.

It is one of the features of my invention that the joint of the transom and side wall is made some distance inside the stern corner of the boat and is perpendicular to the flat bottom. In this way the welded joint holding the sides is separated from the point of maximum stress and a substantially stronger construction results.

Another feature of my invention is the inclusion of a rigid plastic foam incorporated into the construction of the seat thereby providing substantial added buoyancy to the boat when swamped and simultaneously solidifying the entire structure against twisting stress. Thus the seats also serve as transverse braces supporting the side walls and preventing fiexure of the bottom and the rigid foam holds the seats against buckling during such stress.

Yet another feature of my invention is the construction of a one-piece hull formed by bending the side walls and transom upwardly and together from a single sheet of aluminum.

Further objects and features of my invention will best be understood and appreciated from a detailed description of a preferred embodiment thereof selected for purposes of illustration, and shown in the accompanying drawings in which:

FIG. 1 is a view in perspective of a pointed bow boat;

FIG. 2 is a plan view thereof;

PEG. 3 is a fragmentary view in perspective of a joint formed of the transom and a side wall;

FIG. 4 is a fragmentary view in perspective, partially cut away, showing the junction of a seat and side wall with the rigid plastic foam in place; and

'FIG. 5 is a plan view of the aluminum sheet after cutting and prior to bending.

The preferred embodiment of my invention herein shown is made of light-weight substantially rigid aluminum. A sheet of suitable aluminum is cut as in FIG. 5 so as to form a bottom section 10, side sections 12, 14 and a transom section 16. The sheet is cut so that when the side walls 12, 14 are bent upwardly from the bottom 143 along bend lines 17, 18 the lower edge 20 of the side wall 14 will meet the curved edge 22 of the bottom 10, and the bottom edge 24 of the side wall 12 will meet the curved edge 26 of the bottom It This operation requires that the side walls 12, 14 be bent inwardly as well as upwardly until the bow edges 28, 3%) meet. The bow edges 28, 30 are joined securely by welding. The bottom edges 2t 24 of the side walls 14, 12 incline slightly toward the top edges of the side walls as they approach the bow edges 28, 30. Hence the bottom 10 must also be bent slightly upward to meet the bottom edges of the side walls. A weld joins the curved edges 22, 26 of the bottom It) to the bottom edges 20, 24 of the side walls 14, 12. These three welds complete the fabrication of the shape of the how.

The transom section 16 is bent upwardly from the bottom iii along the transom bend line 32 until it is substantially perpendicular thereto as shown in FIG. 3, where the side wall 1 and transom 16 are shown.

The side walls i2, 14 are formed at their stern ends with a corner section 34, 36 taking substantially the form of a right triangle. In FIG. 3 the corner section 34 is shown. In fabricating the boat the corner sections 34, 36 are bent at right angles to the side walls 14, 12 along the corner bend lines 33, 4h. The corner sections 34, 36 are then lying in the vertical plane defined by the transom section 16. The edges 4-2, 4 of the corner sections 34, 36 then abut the ends of the transom section 16, and are welded thereto. It is to be noted that these welds are perpendicular to the bottom it? and spaced inboard of the stern corners of the boat.

This stern construction greatly improves the durability of t re transom joints in the presence of vibrations such as those set up in the transom by an outboard motor, which may be mounted on an outboard motor support panel 37 on the transom 16. The increase in durability is achieved because the joint is positioned in the field of vibration such that the vibrations can pass through it to the corner sections 34, 36 in a substantially straight line. In customary construction where the transom and side Wall are joined substantially at right angles, the vibration tends to bend and weaken the welded joint which is much more vulnerable to breakage due to such forces than are the simple bend lines of the metal 38, 46'.

Three seats are provided running the width of the boat and attached at their ends to the side walls l2, 14. One

seat is positioned near the stern, one near the bow, and one substantially in the middle of the boat.

The seats are su-bstmtially identical in construction, although the actual dimensions differ somewhat, therefore, the stern-most seat only will be described.

FIG. 1 shows a stern seat. The seat iscomprised of a seat member 46, which is also shown in fragmentary view in FIG. 4. The seat member 46 is formed from aluminum sheet which is bent to provide a top face and forward and aft faces, taking the general configuration of a fiat bottomed U mounted closed end up. End side edges 48 of the seat member 46 are cut to fit flush against the side walls 12, 14, and also to provide a limber hole 50 through the seat member 46 to permit water accumulating in the boat to flow from one compartment to the next.

In order to fasten the seat member 46 to the side walls '12, 14 a bracket (not shown) is first attached to the side walls 12, 14. The bracket is formed to present faces over which the ends of the seat member 46 may be fitted and to which it may be attached by screws, nuts and bolts, rivets, or other suitable means.

A block of rigid plastic foam 52, for example, Styrofoam, is contained in the chamber formed by the seat member 46 and bottom It The foam block 52 is substantially rectangular in shape and is provided for the purpose of adding buoyancy and rigidity to the boat.

The seat construction employed has a three-fold purpose. First, it provides a seat for the passengers in the boat. Secondly, it provides the needed bracing between the side walls 12, 14 and the bottom 16 to make the boat substantially rigid. This ri idity is customarily achieved only by means of a plurality of braces which interfere with easy and safe movement of passengers. Thirdly, the seats provide a buoyancy chamber.

Three keels 54, 55, 56 are attached to the underside of the bottom 10. These are constructed of T-shaped aluminum stock positioned parallel to each other and to the longitudinal plane of the bottom 10. The keels 54, 55, 56 serve three purposes. They add to the rigidity of the boat structure. They aid in reducing drift of the boat and stabilize it. They also provide runners so that the boat may be used on ice when the propulsion is provided by an air motor and in general allow the boats to more easily ride up and over obstructions in its path.

Gunwales are provided formed from aluminum channeling and fitted over the upper edge of the side walls 12, 14 and transom 16. The gunwales are secured to the walls by screws or other suitable fasteners.

The points at which the gun-wales join, the ends, of the transom l6 and the bow, are fitted with cast aluminum corner pieces 58, 60, 62. The corner pieces 58, 6% s2 are channeled in their underside to allow them to be fitted down on the gunwales to which they are secured by screws. The corner pieces 58, 6t), 62 serve two purposes. One is to provide a neat safe joining of the gunwales to the edges of the sides and transom. The other is to give added strength along the line of the top of the side walls 12, 14 and transom 16.

In order to provide some extra support for the side walls 12, 14, small triangular aluminum struts 64, 66 may be fastened between the side walls 12, '14 and the top of the middle seat member.

It may be readily appreciated that a boat formed and assembled as above described has provided solutions to many of the problems which herefore perplexed the lightweight metal boat industry. The described craft is cut from sheet aluminum. There are no compound curves which have to be stamped by expensive dies. There is no necessity for extra bracing which interfere with the passengers movement.

Since numerous minor variations of the preferred embodiment of my invention herein described will now be apparent to those skilled in the art, it is not my intention to confine the invention to the precise form herein shown,

but rather to limit it in terms of the appended claims.

Having thus described and disclosed a preferred emd bodiment of my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a boat hull construction the combination of a single sheet of material having a bottom portion, side walls and a transom, said side walls inclined angularly outward from the bottom portion and each having a free end bent to lie in the plane of said transom, the transom being of less width than the lateral distance between the upper edges of the opposing side walls, said free ends of said side walls joined to the transom along seams substantially normal to the plane of the bottom portion with said seams spaced from the stern corners of said hull so said free ends and transom lie in abutting relation in a common plane. a

2. A metal boat as defined in claim 1 further characterized by said seats having a top and sides of unitary construction, means for attaching said seats to said sides, and rigid plastic foam within said seats whereby said seats give added rigidity to said boat and contain means for preventing said boat from sinking when submerged.

3. A metal boat as defined in claim 1, further characterized by at least two keels attached to the under surface of said bottom and normal to the plane thereof whereby said boat is strengthened and may be used'interchange ably on water or ice. 7 r

4. In a boat, a transom joint construction wherein the side wall is bent inboard substantially at right angles to itself, an edge on said inboard bent side wall substantially perpendicular to the water line, a transom section of less width dimension than the intended stern, an edge on said transom section similarly substantially perpendicular to the water line, and means including a weld for joining said substantially perpendicular edges whereby a joint inboard of the stern corners of said boat is formed which joint is substantiallyperpendicular to the water line and passes vibrations set up in said transom with little tendency to open said joint.

5. A boat having in combination; a single piece hull of sheet metal bent to provide a bottom, a pair of sides, and a transom, said sides and transom defining between them stern corners of the boat; said transom including a section terminating inboard' of said stern corners, and said sides each bent around said stern corners into the plane of said transom; said transom section welded to each said side along a line located substantially inboard of said stern corners; and means including transversely extending seats secured to said sides and bottom for supporting said boat against twisting stress.

6. A boat as defined in claim 5, further characterized by said seats being of one-piece construction having a top face, and two side faces; said faces'defining limbers whereby bilge drainage is facilitated; means comprising rigid plastic foam contained within said seats and extending downwardly into contact with the bottom whereby the seat members are strengthened and flotation means is provided.

7. A boat as defined in claim 5, further characterized by gunwales comprising channel members fitted over the top edges of said sides and transom; means for securing said gunwales to said side and transom edges including castings grooved on their underside to receive said gunwales where they meet at angles.

8. A boat as defined in claim 5, further characterized by a plurality of keels extending the length of said bottom on its underside and substantially normal to the plane thereof, said keel being a suitable length of metal T section.

9. A boat as defined in calimS further characterized by a plurality of parallel keels extending the length of said bottom, said keels being formed of suitable lengths of metal T section.

gitudinally extending side walls and a laterally extending transom, said side walls having tapered forward ends joined in abutting relationship, the transom being of less width than the distance between the opposing side walls, each of said side Walls having a bent section extending inwardly adjacent the rear ends thereof, the side edges of said transom joined to the said inwardly bent sections of said side Walls in the plane of the transom and spaced inwardly of the stern corners.

11. In a boat hull construction as set forth in claim 10 where seat members laterally extend between the opposing side walls and are secured thereto, said members having a rigid plastic foam member depending downwardly from the under surface thereof into contact with the bottom portion defining a buoyant structural support therefor.

References Cited in the file of this patent UNITED STATES PATENTS Watters Dec. 3, Miller Jan. 12, Harris Oct. 11, Lermont Mar. 2, Hoppenstand Oct. 23, Lindsey Nov. 27, Tykwinski Jan. 22, Kehn Aug. 23, Snider Jan. 31, 

